This invention relates to an air-cooled X-ray tube with X-ray shielding material incorporated directly on the tube envelope.
High powered X-ray tubes, for example, those producing X-rays at voltages of 75 to 150 or more KV, develop a substantial amount of heat during operation. A rotating anode prevents damage to the anode itself during the high voltage, high temperature operation; however, the entire tube heats up and must be cooled in order to run continuously or frequently.
High powered X-ray tubes generally comprise a glass tube envelope in which an anode is rotatably mounted adjacent a cathode. The anode is mounted on a shaft with a rotor of an AC motor. The tube envelope is immersed in an oil bath for cooling purposes, providing good heat transfer from the tube envelope walls, and the oil may be circulated for cooling. The stator for driving the rotor and hence the anode is also located in the oil bath, surrounding the tube envelope and the rotor.
The oil bath method of cooling has many drawbacks. It increases the size and complexity of the overall X-ray tube apparatus, and creates difficulties in installing and replacing tubes. The oil must be contained in a sealed enclosure, and the entire oil bath container is generally shielded against loss of stray radiation.